In recent years, studies are underway on dry processes for cutting process, grinding process and the like as environmentally friendly methods for metal working processes. When metal working is conducted in a dry condition, the processing point needs to be cooled. The processing point is cooled, for example, by spraying compressed cooling air or the like. However, since a completely dry process lacks lubricity between the instrument and a work material, a very small amount of lubricating oil is supplied. Examples of the working method include a processing method for nonferrous metal (for example, see Patent Document 1), conventionally known metal working oil compositions (for example, see Patent Document 2, 3) and the like. As for these metal working oil, a new working oil which is capable of further improving workability, extending the life span of the instrument and reducing the amount of oil to be supplied is desired in view of increasing the productivity and/or saving energy. A metal working fluid to which phosphatidyl choline is added is also known (see Patent Document 4).
Patent Document 1 JP 2001-239437 A
Patent Document 2 JP 2000-256688 A
Patent Document 3 JP 2004-300317 A
Patent Document 4 JP 09-57537 A